In the strictest sense of the term 'virus', there are none at the moment in the mac world. There are of course trojans, worms, hacks and hijacks but they operate a bit differently to your conventional virus. You will find that a lot of the reported 'viruses' are in fact trojans.
https://discussions.apple.com/docs/DOC-2435
I've used Bitdefender for over a year and it has worked flawlessly for me.